It is well known that plasmas can be generated and used for altering substrate surfaces through either deposition or etching processes. In etching processes, the depth of the etching into the substrate surface can be an important consideration. On the other hand, in deposition processes, the resultant build-up on a substrate surface can be an important consideration. For instance, the operational applications of many of the high-performance chips and wafers require that the etching or deposition depths be uniformly controlled. It happens, however, that some substrate surfaces will be more resistive to an etching action than will others, and that some substrate surfaces can be more easily worked with during a deposition than others. Accordingly, the differences between substrate materials, and the eventual operational requirements of the etched substrate, must be accounted for. Stated differently, it is desirable to have as much control over the rate and effect of a plasma etching or deposition process as is possible.
One method for controlling ion bombardment of a substrate surface is to control the velocity at which ions impact against the substrate surface. Control of this velocity can be accomplished by controlling the acceleration of the ions. Practical aspects, however, require that the apparatus used to accomplish acceleration control be physically robust and technically precise.
In light of the above, it is an object of the present invention to provide an apparatus and method for altering a substrate surface which is capable of taking all ions in a plasma to a common translational velocity regardless of their initial boundary conditions. It is another object of the present invention to provide an apparatus and method for altering a substrate surface which is capable of controlling, establishing, and maintaining the common translational velocity of ions in a plasma. Yet another object of the present invention is to provide an apparatus and method for altering a substrate surface which is relatively, technically uncomplicated, and which has minimal components for generating crossed electric and magnetic fields inside a vacuum vessel chamber. Still another object of the present invention is to provide an apparatus and method for altering a substrate surface which is simple to manufacture, easy to use, and comparatively cost effective.